A study by researchers from the University of Edinburgh and the National Institute for Public Health and the Environment in the Netherlands has found that nanoparticles, such as those found in air pollution, can travel into the blood and accumulate in diseased blood vessels. The study, published in the journal ACS Nano, suggests that air pollution nanoparticles are able to get into the bloodstream to cause heart disease.
This research shows for the first time that inhaled nanoparticles can gain access to the blood in healthy individuals and people at risk of stroke. These nanoparticles tend to build-up in diseased blood vessels where they could worsen coronary heart disease—the cause of a heart attack.
The findings build on previous studies that have found tiny particles in air pollution are associated with an increased risk of cardiovascular disease, although the cause remains unproven.
It is not currently possible to measure environmental nanoparticles in the blood. So, in complementary clinical and experimental studies, the researchers used gold nanoparticles to evaluate particle translocation, permitting detection by high-resolution inductively coupled mass spectrometry and Raman microscopy.
Gold was detected in the blood and urine within 15 min to 24 h after exposure, and was still present 3 months after exposure. Levels were greater following inhalation of 5 nm (primary diameter) particles compared to 30 nm particles. Studies in mice demonstrated the accumulation in the blood and liver following pulmonary exposure to a broader size range of gold nanoparticles (2–200 nm primary diameter), with translocation markedly greater for particles < 10 nm diameter. Gold nanoparticles preferentially accumulated in inflammation-rich vascular lesions of fat-fed apolipoproteinE-deficient mice.
Furthermore, following inhalation, gold particles could be detected in surgical specimens of carotid artery disease from patients at risk of stroke. Translocation of inhaled nanoparticles into the systemic circulation and accumulation at sites of vascular inflammation provides a direct mechanism that can explain the link between environmental nanoparticles and cardiovascular disease and has major implications for risk management in the use of engineered nanomaterials.—Miller et al.
Mark R. Miller, Jennifer B. Raftis, Jeremy P. Langrish, Steven G. McLean, Pawitrabhorn Samutrtai, Shea P. Connell, Simon Wilson, Alex T. Vesey, Paul H. B. Fokken, A. John F. Boere, Petra Krystek, Colin J. Campbell, Patrick W. F. Hadoke, Ken Donaldson, Flemming R. Cassee, David E. Newby, Rodger Duffin and Nicholas L. Mills (2017) “Inhaled Nanoparticles Accumulate at Sites of Vascular Disease” ACS Nano doi: 10.1021/acsnano.6b08551